1. Field of the Invention
The present invention relates to an engine control apparatus for a vehicle and to a vehicle incorporating the same. More particularly, the present invention relates to an engine control apparatus configured to adjust the amount of intake air supplied to an engine, and to a vehicle incorporating the same.
2. Description of the Background Art
The Japanese Patent Document JP-A-2010-7585 discloses an engine control system which increases an intake air flow rate above a flow rate prescribed for a normal idling state, to increase a engine speed to approach a target idle speed, in order to activate an exhaust air purifying catalyst in an early stage during a warm-up operation immediately after starting of an engine. The engine control system of JP-A-2010-7585 stops increasing the amount of intake air, and performs a feedback control on the engine speed with a normal amount of intake air after a predetermined time has elapsed.
However, in the engine control system disclosed in Japanese Patent Document JP-A-2010-7585, since the amount of intake air is configured to be switched when the predetermined time has elapsed, increase in the engine speed is delayed when the water temperature or the oil temperature is low and friction is high, so that the predetermined time has elapsed and the amount of intake air is switched to a smaller value before the engine speed reaches a target idle speed, which may reduce the engine speed at the time of the switching and cause a variation that the engine speed is momentarily reduced.
Therefore, in order to prevent such a phenomenon, switching the timing of the change in the amount of intake air to a time point when the target idle speed is reached is contemplated. However, when an operator opens a throttle to increase the engine speed, the engine speed temporarily increases to a level higher than the target idle speed, and hence the amount of intake air is switched to a smaller value. Consequently, since the feedback control is performed with a smaller amount of intake air at the time point when the throttle is returned, the problem that the engine speed reduced temporarily is not resolved.
Accordingly, it is one of the objects of the present invention to provide an engine control apparatus which is free from a variation in engine speed by reducing a convergence time of the engine attaining a target idle speed in switching control of the amount of intake air in a case where engine friction at a low temperature is high.